https://scientific-programs.sc....ience/wiki/Cat_Flap_
A cat flap lets you to give your pet more freedom while avoiding the hassle of having to let them in and out. It will also make your pet be less stressed and stop them from entering the house when they are not wanted. To put up a cat flap take a measurement of the distance from the bottom of the cat's stomach down to the floor. Draw a line across the door panel. Make sure is level using an ad hoc level. 1. The type of door If you're installing the cat flap to the uPVC door panel or a double glazing glass sealed unit it